Banshee Ben

iTrader: (4)

My car has been running bad for a while now and I pulled the code. It says my o2's are bad. This doesn't surprise me because my car is super rich and kills my wideband after a few weeks. (it's an off road car so a few weeks is a season)

1. Does the factory computer slowly learn the o2 readings and change the map.
2. Or does the computer read the 02's as bad and just add fuel to be safe.
3. If it learns and slowly modify fuel; when I add the new o2's how long will it take to "re-learn" and get bake to when the custom tune was first done and ran right.

(turbo ls6 with a SD tune, no MAF)

69LT1Bird

iTrader: (1)

Why not get this problem fixed? The computer will try to reset the trims but if it not tuned right it will never be right anyways.

Banshee Ben

iTrader: (4)

I don't want to take it back to the tuner, didn't like what they did, and I need to find someone that I trust. Also I plan on a cam in the near future and will tune it then.

When will the computer "reset" when it detects new sensors?

I go on vacation and run about 200 miles. Basically I'm asking will I spend the whole trip with a blubbering engine while it adjusts for the new sensors.

Harder to do but I could meet up with the tuner and reload the map when they finished, assuming he still has it.

69LT1Bird

iTrader: (1)

New O2 sensors will not fix a problem with the tune. All they are trying to do is get you back to stoich. That may mean that they are trying to add or subtract a bunch of fuel and the trims will be off in either direction. There is no magic cure for a bad tune. You will just damage more O2's until the tune is done correctly.

edcmat-l1

iTrader: (10)

If you're not going to get it dialed in right, just unplug the O2s. It'll just force it into open loop, and not even look at the O2s for reference.

Banshee Ben

iTrader: (4)

Well it ran descent when new, it was just rich. Under boost low 11's upper 10's. This seems to kill the o2's. My WB o2 last about 50 hours.

"New O2 sensors will not fix a problem with the tune. All they are trying to do is get you back to stoich. That may mean that they are trying to add or subtract a bunch of fuel and the trims will be off in either direction. There is no magic cure for a bad tune. You will just damage more O2's until the tune is done correctly."

I understand they +/- fuel trims. Do they do this on each start up? Ie; do they start with the factory flash then modify from there, so when you turn the key off it's like it never happened. Or do they modify and change the factory flash so the next time you start it is already modified and cumulative?

Thanks for the input guys.

69LT1Bird

iTrader: (1)

If the long term fuel trims (LTFT's) are turned on in the tune it is cumulative. If off, the shorts try to correct on their own.

wait4me

iTrader: (10)

To answer your question, the computer always looks at the 02 sensors when the car goes into closed loop. It works very fast to trim up or down your fuel to bring it back to where it "thinks" it should be. This is always changing while the engine is running. With a scan tool you can watch how it works. It will fully make its changes all the time. Even if you swap a new one while the engine is running, it would just start to use the new readings and adjust from there.